Singer Bryan Adams has cancelled his Christchurch concert following a mass shooting at two mosques that has left 49 people dead and nearly as many injured.

The 59-year-old Canadian songwriter was due to appear at Hagley Park in the New Zealand city on Sunday, but has since put the concert on hold following the tragic attack.

Adams tweeted the live-music event would be cancelled in 'solidarity with the victims of the mass murder yesterday'.

Singer Bryan Adams has cancelled his Christchurch concert following a mass shooting at two mosques that has left 49 people dead and nearly as many injured

The 59-year-old Canadian songwriter was due to appear at Hagley Park in the New Zealand city on Sunday, but has since put the concert on hold following the tragic attack

The suspected gunman, 28-year-old Australian citizen Brenton Tarrant (pictured), will appear in Christchurch District Court charged with murder on Saturday, following a mass shooting Friday afternoon at the Al Noor mosque which was live-streamed - a second attack also happened at Linwood Masjid

The suspected gunman, 28-year-old Australian citizen Brenton Tarrant, appeared at Christchurch District Court charged with murder on Saturday, following a mass shooting Friday afternoon at the Al Noor mosque which was live-streamed - a second attack also happened at Linwood Masjid.

The cancellation of the concert comes only 12 hours after Adams tweeted his 'heart goes out to all the families of the victims of today's horrific mass shooting'.

Concert organiser Neptune Entertainment director Toby Burrows said staff who were preparing the Hagley stage were promptly evacuated following the attack.

Police Commissioner Mike Bush confirmed on Twitter that the death toll stands at 49, with 42 injured.

Prime Minister Jacinda Ardern confirmed two of the 40 people being treated at Christchurch Hospital were in a critical condition - a five-year-old had also been taken to Starship Hospital at Auckland.

Ms Ardern has also vowed to toughen the country's gun laws after she said the attacker had used five firearms in the attack, including two semi-automatic weapons, two shotguns and a lever action firearm.

She said she had been advised the gunman obtained a Category A licence in November 2017, and 'under that, he was able to acquire the guns that he held'.